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PDBsum entry 3erb
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References listed in PDB file
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Key reference
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Title
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The structure of c2b, A fragment of complement component c2 produced during c3 convertase formation.
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Authors
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V.Krishnan,
Y.Xu,
K.Macon,
J.E.Volanakis,
S.V.Narayana.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2009,
65,
266-274.
[DOI no: ]
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PubMed id
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Abstract
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The second component of complement (C2) is a multi-domain serine protease that
provides catalytic activity for the C3 and C5 convertases of the classical and
lectin pathways of human complement. The formation of these convertases requires
the Mg(2+)-dependent binding of C2 to C4b and the subsequent cleavage of C2 by
C1s or MASP2, respectively. The crystal structure of full-length C2 is not yet
available, although the structure of its C-terminal catalytic segment C2a has
been determined. The crystal structure of the N-terminal segment C2b of C2
determined to 1.8 A resolution presented here reveals the arrangement of its
three CCP domains. The domains are arranged differently compared with most other
CCP-domain assemblies, but their arrangement is similar to that found in the Ba
part of the full-length factor B structure. The crystal structures of C2a, C2b
and full-length factor B are used to generate a model for C2 and a discussion of
the domain association and possible interactions with C4b during formation of
the C4b-C2 complex is presented. The results of this study also suggest that
upon cleavage by C1s, C2a domains undergo conformational rotation while bound to
C4b and the released C2b domains may remain folded together similar to as
observed in the intact protein.
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Figure 3.
Figure 3 Topology representation of individual CCP domains of
C2b. Successive individual  -strands
are labeled A-H and are colored as in Fig. 2-. Topology
representations are shown for (a) a typical CCP domain and the
individual CCP domains of C2b: (b) CCP1, (c) CCP2 and (d) CCP3.
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Figure 6.
Figure 6 Model of full-length C2 in ribbon representation. The
N-terminal CCP1 (red), CCP2 (gold), CCP3 (yellow), CCP3-vWFA
linker (blue), vWFA domain (cyan) and SP domain (magenta) are
represented and the MIDAS and SP catalytic site are indicated
with arrows.
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The above figures are
reprinted
by permission from the IUCr:
Acta Crystallogr D Biol Crystallogr
(2009,
65,
266-274)
copyright 2009.
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